1. Field of the Invention
This invention relates to a collared fuel injection pipe for engines.
2. Description of the Prior Art
For a conventional fuel injection pipe for automobile engines, usually a drawn fine pipe of an outside diameter of 6 to 8 mm and inside diameter of 1.6 to 2 mm is used, a head 2 is made by a cold buckling method and a neck 3 is formed in the boundary part of the head hardened by buckling and the pipe shaft part not buckled. Generally, in case the injection pipe is vibrated, the neck 3 will become a fulcrum of the vibration and will be therefore often unavoidably broken. Therefore, since long ago, as a reinforcing measure, as shown in FIG. 1, the neck has been reinforced by the pressed contact of the curved surface 4 of the neck 3 and the curved surface 6 of a collar 5 with each other. However, as there is a clearance on the entire outside surface of the pipe except the pressed contact part between the curved surfaces 4 and 6, the fulcrum of the vibration will be located near the neck which will be thus likely to be broken.
If the collar 5 can be pressed and fitted to the outside surface of the pipe below the neck, even the conventional pipe will be able to be expected to be strengthened. However, it has been impossible due to a very high friction resistance to press and fit the collar 5 through the long pipe 1 extending below the neck. Shown in FIG. 2 is a type known as a Benz type having a step 7 on the pipe 1 near one end of the collar 5. It is shown together with the conventional product of FIG. 1 for comparison with the product of the present invention.